DVORAK

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Context:  American meteorologist Vernon Dvorak passed away at the age of 100. In the era of advanced satellite technology, Machine Learning (ML), Artificial Intelligence (AI), this key technique, named after him, continues to be widely relied upon by forecasters till date.

Who was Vernon Dvorak ?

• Dvorak was an American meteorologist best credited for developing the Dvorak (read as Do-rak) technique in the early 1970s.
• The technique has been upgraded multiple times since then, and after a recent software update in May this year, it has been named the Advanced Dvorak Technique (ADT), coined by the National Hurricane Centre of the National Oceanic and Atmospheric Administration (NOAA).
• The updated technique, the American meteorologists had said, would improve the tropical storm forecasts by many folds as they would have access to sharper and detailed images than ever before.

What is the Dvorak technique?

• It was first developed in 1969 and tested for observing storms in the northwest Pacific Ocean.
• Forecasters used the available satellite images obtained from polar orbiting satellites to examine the features of the developing tropical storms (hurricanes, cyclones and typhoons). During day time, images in the visible spectrum were used while at night, the ocean would be observed using infrared images.
• The Dvorak technique was a cloud pattern recognition technique based on a concept model of the development and decay of the tropical cyclone, according to a 2006 research paper published in the journal of American Meteorological Society.
• From the satellite images thus obtained, the Dvorak technique helps forecasters to do a pattern recognition from the observed structure of the storm, locate its eye and estimate the intensity of the storm
• Through this statistical technique, scientists are able to measure the cyclone’s convective cloud pattern — curved bands, eye and central dense or cold region and shear.
• It is the Dvorak technique which gives the best estimates of the cyclone intensity — a vital component while issuing weather warnings.
• This tool, experts claim, cannot help make any predictions, measure wind or pressure or any other meteorological parameters associated with the cyclone.
• But it is a guide to estimate the storm’s intensity and possible intensification — which is crucial for local administration in planning evacuation measures of coastal or other nearby residents.
• The veteran meteorologist had also presented the wind speed and associated category of the tropical cyclone, making it a near-perfect tool for the operational cyclone forecasters.

Why is technique still widely in use?

• Unlike land, ocean observations in the 1970s were sparse.
• Today, there continues to be an improved network of land-based meteorological observations, either in the form of taking manual observations, installing automatic weather stations or automatic rain gauges.
• On the other hand, ocean observations still remain limited. There are many vast regions across the four oceans that have not been fully examined with meteorological instruments.
• Ocean observations are mostly taken by deploying buoys or dedicated ships, but the number of observations from the seas is still not sufficient across the world.
• That is why meteorologists have had to depend more on satellite-based imageries, and combine it with the available ocean-data at the time of forecasting the intensity and wind speed of the tropical cyclones.
• The Dvorak technique, said to be one of the greatest meteorological innovations, has undergone several advancements since its inception.
• Even in the present day, when forecasters have access to several state-of-the-art tools like model guidance, animations, artificial intelligence, machine learning and satellite technology,
• it is the advanced versions of the 50-year-old technique that continues to be widely used. It has saved the lives of millions of people across the world and will continue to do so.

https://indianexpress.com/article/explained/explained-climate/dvorak-cyclone-intensity-estimation-technique-explained-8165811/